Disclosed is a transmission power control method for comparing the error rate of receive data and a target error rate in an apparatus on the receiving side, controlling target SIR (performing outer-loop control) and controlling transmission power on the transmitting side in such a manner that measured SIR will agree with the target SIR. In outer-loop control, it is determined whether an interval is an interval in which data is being transmitted and (1) in an interval in which data is being transmitted, the target SIR is controlled upon comparing the error rate of receive data after decoding and the target error rate, and (2) in an interval in which data is not being transmitted, the target SIR is controlled upon measuring error rate of a demodulated pilot or of a synchronous word and comparing the measured error rate of the pilot and a target error rate of the pilot.